Auto Power Control (Apc) - Ricoh B089 Service Manual

2.4.2 AUTO POWER CONTROL (APC)

LD LEVEL
LD ON
LD OFF
LD OFF
VIDEO
The LD driver IC drives the laser diode. To prevent the intensity of the laser beam
from changing because of the temperature, the machine monitors the current
passing through the laser diode (LD). The machine adjusts the current to the laser
diode by comparing it with the reference level from the reference circuit.
This auto power control is done just after the machine is turned on and during
printing while the laser diode is active.
The laser diode power is adjusted on the production line.
NOTE: Do not touch the variable resistors on the LD unit in the field.
SM
LD Driver
LD
LD
Controller
VIDEO
VREF
LD Drive Board
2-23
LASER EXPOSURE
+5V
PD LD
Reference
Circuit
B027D510.WMF
Monitor
B089/B093